Large Format Negative Digitization




Introduction: Large Format Negative Digitization

My wife recently returned from a trip to visit family with a stack of large format (not 35mm) negatives. I have a 35mm negative feature built into my multi-function printer but didn't have anything that would fit these negatives. I did some research and professional tools were far too expensive, I searched for DIY solutions and took some ideas from a few of them. What I came up with was cheap, easy to build and produced results I am happy with.

Materials for the Base:

  1. Scrap wood to build the base (or premade wood box as I found)
  2. Scrap wood for the upright arm. I used 3/4" plywood scrap about 24" long
  3. 2-3 wood screws to attach the upright to the base

Materials for the light table:

If you have a light table you might be able to skip some of this

  1. A tablet with a screen based light application
  2. 2-3 pieces of plexiglass or glass. If you can find frosted or white Plexiglas that might be ideal.
  3. Self adhesive rubber feet. I used flat black square ones that I could stack double thick.

Camera and Mounting Hardware:

  1. A DSLR or similar camera
  2. A 1/4" screw (or whatever fits your camera tripod mount)
  3. A scrap chunk of wood to use as a buffer between the upright arm and the camera


  1. Handheld screwdriver/drill
  2. Drill bit that matches or is slightly larger than the diameter of the screw (1/4" in my case).
  3. A square would help but you could probably get by without it

Software Links:

Step 1: A Little Artistic Credit

I have a 5 year old daughter who upon seeing the rig said "I love your invention daddy." "We should decorate it." The artwork is all hers and I appreciate her contribution.

Step 2: Getting the Right Hardware

The whole idea is to mount the camera pointing toward a fixed flat surface. I looked around my garage and found a strip of plywood and a wooden box that were perfect for the project.

Once you have the base you will need an upright arm and a buffer. The upright arm needs to be strong enough to hold the weight of the camera and the buffer piece is just meant to keep the arm from being in frame. I used a piece of plywood scrap about 24" long for the arm and a buffer of about 5/8" thick.

Depending on your arm and buffer hardware you will need a corresponding length of screw. I used 1/4" -20X 1-1/2" machine screw.

Step 3: Build the Base

You might need to build a base but I was lucky. I am sure you can find an appropriate Instructable to help you with this step.

Once you have the base you want to attach the upright perpendicular to the base. It doesn't need to be perfect or perfectly centered but do the best you can with what you have.

Step 4: Camera Mount

For the mount you need the upright that you attached in the prior step, the buffer, the mounting screw, drill bit and your handheld drill.

Consider the focal length of your lens of your camera when you determine the height of the mount. You want to put the negatives as close to the camera as possible but having some ability to zoom in or out is good too.

Drill a hole through the upright and the buffer to fit the screw. Dry fit these pieces by screwing the screw through the upright, the buffer, and into your camera in that order. Please be careful not to over tighten and damage your camera.

If the camera is held tight enough that it doesn't swing you are good, if it is not pulled flush against the buffer block you might need a larger buffer. You could also use washers if you wanted. If it is too short you might need to use a Forester or paddle bit to recess the head of the screw (see my pictures).

Step 5: Assembling the Light Table

The idea here was to use the even light provided by my wife's tablet to develop the negatives. I first tried to just place the negatives on top of the tablet. It worked pretty well but when you magnified the images you could see the pixels of the tablet bleed through. I needed to diffuse the light without reducing it too much.

I went to the hardware store with hopes of finding frosted or white Plexiglas but only found clear. What I did was purchased 3 pieces, left the protective film on one, attached feet to the second (which raised it up allowing some distance for the light to diffuse). The third I used to place over the negative to hold it flat.

Step 6: Taking the Pictures

This took a little work to get just right. I first tried the snapshot mode with flash disabled. That worked OK but the exposure wasn't always right. What I ended up doing was using a bracketed exposure taking 3 pictures of each negative, one automatically calibrated, the second slightly underexposed, and the third slightly overexposed.

On my D-SLR this is a built in feature, I just held the shutter button down while it snapped three shots and then switched negatives.

Once during the process the diffuser slipped out from under the rest of the sandwich. You can see from my picture the result and the impact of the diffuser in the process.

Step 7: Processing the Negatives

Sorry for all of the Mac and Windows users out there, you really should try Linux. I am a Linux primarily so the software I used is Linux based. I believe the same software would work for OSX but in any case you can find photo editing software to do the same.

I used the command line utility that comes with Imagemagick called simply "convert." There is a negate parameter that you can pass in followed by the source file and the destination file. The command to convert one image is:

convert -negate IMG_8560.JPG IMG_8560.JPG

This specific command would replace the image with the negated version of same. I didn't want to keep a bunch of negative images around so I was OK with that. You could give it a new name like:

convert -negate IMG_8560.JPG newname.JPG

I wrote a little bash script to find all the files in the current directory and replace convert them using the first command. Download the file, give it execute permissions (change the extension back to sh for clarity).

Within the command prompt navigate to the folder containing the negatives and execute It will print some output for each conversion but in the end return to the prompt. Once done you should have the images ready for cleanup.

Step 8: Cleaning Up the Images

I wanted to clean them up and make them look as good as possible. I used Darktable to crop the edges, rotate a little as needed, and automatically "fix" exposure. Since I did bracketed exposures I have three finished images to select from.



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    16 Discussions


    2 years ago

    I don't use ImageMagick, (but am a Linux!). In your convert/negate step, it may be better to convert from JPG to either PNG/PPM if you are going to be doing any further editing -- even for just cropping/rescaling/rotating, never mind retouching, before finally saving back to JPG at the very end.

    This saves an extra step of JPG re-compression. Working in "raw mode" from the camera would also help, if you have the tools to understand the raw camera output :)

    7 replies

    I did actually try to edit the raw files but couldn't figure out how to negate the CR2 image files that my canon writes. I pretty generally use the Raw + JPG mode on my camera but really haven't played with the CR2 files If you have any pointers that would be awesome.

    Better answer - Use the invert module in darktable. It's in the basic group, but you may have to add it from the more modules at the bottom

    I did actually try using the invert function in darktable on a cr2 file and ended up with the results below.


    I tried again after watching some videos and learning how the invert feature works. I got ok results but in reality the process I went through was a lot less time consuming. The process you suggest would probably be worth it for the best of the images but with a lot of the negatives I had the images just weren't worth more than a few seconds each.

    darktable does have a pretty steep learning curve. I've been using it for over a year and I'm still learning lots of things. If you brought a lot of images into darktable you could process one, copy the history stack from it, then paste the stack to the rest and they would be processed the same.

    Darktable will process the cr2 files. You can invert the image using the contrast setting on the lowpass filter. You could also search youtube for developing negatives with darktable.

    No personal experience with CR2 files (my camera only provides .JPG, so I always load .JPG into GIMP and resave as .XCF (gimp) while editing, or use djpeg to decode to an RGB/bitmap/lossless format for further editing and processing. To save the re-jpegging over and over.

    As for your CR2 files, google "linux canon CR2 viewer" -- I found this, it's ubuntu specific but the packages and steps required look like they would work on other-linux too.

    Brilliant and simple. I'm going to modify it slightly for my 35mm negatives. Thanks!

    This is brilliant in its simplicity. I have a whole bag of Brownie negatives from my grandparents house that i have been wanting to digitize. I looked endlessly for a good negative scanner but none of them have the right format. Then I was thinking like making a light box and so on, over complicating the issue. This is so simple that I already have all the parts and pieces and could get started tonight. I love it.

    I'm pretty sure that you could have simply scanned the negatives. Scanners have white background on the scanning deck. Then you could crop and reverse the image as you did before.

    Excellent method for opaque images like paper prints though.

    3 replies

    When scanning negatives and slides, the light has to be above the object being scanned. These scanners have a light source in the lid. It is unfortunate that they only make these things for 35mm negs and slides.

    This is exactly what i was gonna say. They don't make scanners that have a light source that you can use with negatives that aren't in a 35mm format. Super frustrating.

    I should have mentioned that I tied that but my scanner didn't produce the same quality

    Your photos look awesome! Thank you for sharing your very first instructable. I can't wait to see what you post next!!